IN-ARITHMETIC-THEORY

where term is a term that when evaluated will produce a theory
(see theories), and doc-string is an optional documentation
string not beginning with ``:doc-section ...''. Except for the
variable world, term must contain no free variables. Term is
evaluated with the variable world bound to the current world to
obtain a theory and the corresponding runic theory
(see theories) is then made the current theory. Thus,
immediately after the in-arithmetic-theory, a rule is enabled
iff its rule name is a member of the runic interpretation (see theories)
of some member of the value of term.

Warning: If term involves macros such as ENABLE and DISABLE
you will probably not get what you expect! Those macros are defined
relative to the CURRENT-THEORY. But in this context you might
wish they were defined in terms of the ``CURRENT-ARITHMETIC-THEORY''
which is not actually a defined function. We do not anticipate that users
will repeatedly modify the arithmetic theory. We expect term most often
to be a constant list of runes and so have not provided ``arithmetic theory
manipulation functions'' analogous to CURRENT-THEORY and ENABLE.

BECAUSE NO UNIQUE name is associated with an in-arithmetic-theory event,
there is no way we can store the documentation string doc-string
in our il[documentation] data base. Hence, we actually prohibit doc-string
from having the form of an ACL2 documentation string;
see doc-string.